A closed-loop elevator drive costs more than an open-loop drive because the quoted drive is only part of the system. Closed-loop control adds an encoder on the motor, a PG card that is priced separately, extra encoder cabling and shielding, and longer, more skilled commissioning. If a quotation lists only the drive, it is not yet a like-for-like comparison.
What the extra cost actually buys
In an open-loop drive, the controller estimates motor behaviour from a motor model. In a closed-loop drive, an encoder reports real speed and rotor position back to the drive, so the drive can correct drift, hold torque at zero speed and level more precisely. That feedback is the reason hospitals, high-rise passenger lifts and other levelling-critical buildings specify closed-loop control, as explained in Open-Loop vs Closed-Loop Elevator Drives: How to Choose. The hardware that makes the feedback possible is also the reason the bill is longer.
Cost anatomy: five lines to check on every quotation
| Cost line | What it covers | What to ask before you approve |
|---|---|---|
| Drive | The elevator inverter itself, in the required power and supply class | Is the quoted model open-loop, closed-loop or dual-mode? |
| Encoder | The feedback device fitted to the motor shaft | Is an encoder included, and is it compatible with the existing motor? |
| PG card | The encoder feedback interface between encoder and drive, priced separately | Which PG card type matches the encoder, and is it on the quotation? |
| Cabling and fitting | Encoder cable, shielding, routing and mechanical fitting | Are cable, glands and fitting labour included? |
| Commissioning | Encoder alignment, PG card setup, tuning and levelling tests | How many site visits and retests are included? |
The PG card point deserves emphasis because it is the easiest line to miss. Closed-loop models do not include the PG card as a free extra: it must be selected for the encoder type. Incremental ABZ encoders, SIN/COS encoders for synchronous motors and absolute encoders use different cards, including the 1387, ABZ, MCTC-PG-E, 1313 and MCTC-PG-F1 types. Ordering the wrong card does not save money; it delays commissioning until the correct card arrives.
How to compare closed-loop and open-loop quotes
- List the full system, not the drive alone. Put drive, encoder, PG card, cabling and commissioning in separate rows for each quotation.
- Match the encoder to the card. Confirm the encoder type first, then the PG card type. A card chosen by price alone is a false saving.
- Price the commissioning honestly. Allow for encoder alignment, parameter setup, zero-speed checks and levelling tests across loads.
- Score the building need, not only the first cost. Use the matrix below: if levelling, comfort or zero-speed holding is specified, it belongs in the requirement, not in an optional extra.
- Ask what a revisit costs. A cheaper first installation that needs a second visit for levelling or encoder faults is rarely the cheaper project.
- Request a quotation on the same scope. Send each supplier the motor nameplate, encoder type, building type and levelling requirement so the replies can be compared line by line.
Building selection matrix
| Building type | Closed-loop case | When open-loop can be enough |
|---|---|---|
| Low-rise residential | Choose closed-loop only where levelling or ride comfort is specified | Often sufficient for simple, low-rise passenger or goods duty |
| Freight and goods lifts | Useful where precise stopping under changing load matters | Usually sufficient; the load does not judge small levelling differences |
| High-rise commercial | Strong case: frequent stops, higher speeds and passenger expectations | Harder to justify where the specification demands precise levelling |
| Hospitals | Strong case: stretchers, accessibility and smooth, level stops | Only where the building specification does not require closed-loop performance |
For context on the families behind these choices, the Z3300 open-loop and D3300 closed-loop elevator inverters share a 2.2-45kW platform, while the 11LIFT closed-loop elevator inverter covers 2.2-37kW and supports both open-loop and closed-loop configurations. Before deciding to replace a drive at all, check the 7 signs your lift VFD needs an upgrade: a drive that is failing for other reasons should be judged on condition first, and on loop type second.
Frequently asked questions
Is the PG card included with a closed-loop drive?
No. On the IDEEI closed-loop models discussed here, the PG card is priced separately and must be matched to the encoder type. Always ask for it as a named line on the quotation.
Does closed-loop always cost more over the whole project?
Not necessarily in total project terms. The first cost is higher because of the encoder, PG card and commissioning, but a correct closed-loop installation can reduce levelling rework and callbacks where precise stopping is specified. Compare the full scope, not the drive price alone.
Can I reuse an existing motor encoder?
Only if the encoder type, signal and mechanical fitting are compatible with the selected drive and PG card. Send the motor and encoder details with the inquiry so compatibility can be confirmed before ordering.
Will the most expensive PG card give better levelling?
No, and this is the trap. Levelling improves when the card matches the encoder and the drive is correctly aligned and tuned. A mismatched absolute-encoder card on an incremental encoder does not add precision; it adds a fault to fix.
Is open-loop a mistake for a passenger lift?
Not automatically. Open-loop can suit low-rise, low-demand duty. It becomes the wrong choice when the building specification, passenger expectation or levelling requirement clearly calls for closed-loop feedback.
To compare like with like, send the motor nameplate, encoder type and building type with your inquiry, and ask for drive, encoder, PG card, cabling and commissioning as separate quotation lines.